The present invention generally relates to the mounting and protection of light sensors and their respective beams. More particularly, the present invention is directed towards the rigid mounting of the sensor equipment, combined with the reflecting and blocking of the light beams to provide a more reliable, and usable sensor for product detection in inaccurate product ejection systems.
Sensors have been widely used in the detection of product for many years. Prior art sensor beams utilize long an narrow conical beams for sensing product ejection. In most cases the sensors are used in their original manufactured state and the beams are altered by lenses and covers. This prior art method requires the ejected product to pass through a relatively small target area. When the ejection process is inaccurate, the randomly tossed product is difficult to detect consistently. This is due to the normal ejection error that may result in a product ejection path when the error is greater than twice the size of the area of the product.
In addition to the problems associated with the product ejection area, the variable mounting of prior art sensors has to be adjusted for proper alignment with the product flow. The adjustable mounting causes problems because the sensors may be moved accidentally or intentionally which can cause the sensing units to become mis-aligned and fail to detect the product flow.
A further problem associated with the prior art is the production debris that may be ejected along with the actual product being produced. Production debris has been an ongoing problem to sensors and the buildup of this debris requires a periodic cleaning of the sensor lenses. In dusty or dirty production environments this debris has severely limited or prevented the use of sensors because the constant cleaning down time of the sensors results in lost production time. In addition to the cleaning problems associated with the production debris, other problems, such as false sensing can also be attributed to this debris. If a sensor is designed to detect small products by increasing the resolution of the sensor, then the debris particles can break the sensing beam and result in an inaccurate sensing signal. Consequently, a need remains for a device to overcome these problems.
Previous monitoring or detection systems include U.S. Pat. No. 4,605,850; issued to Anselment et al. on Aug. 12, 1986; U.S. Pat. No. 4,742,337, issued to Haag on May 3, 1988; U.S. Pat. No. 5,583,334, issued to Baumann on Dec. 10, 1996; and U.S. Pat. No. 5,812,058, issued to Sugimoto et al. on Sep. 22, 1998. These patents are hereby incorporated by reference.
U.S. Pat. No. 4,605,850, issued to Anselment et al on Aug. 12, 1986 discloses a LIGHT BARRIER APPARATUS FOR MONITORING DOORWAYS. This patent teaches a device that has a central mount with a transmitter and a receiver that are mounted on a dye-cast support element. The design has two deflecting mirrors mounted on adjustable universal joints within a housing to deflect a beam of light to the receiver. The principal object of this invention is to provide a light sensor apparatus that does not require the whole apparatus to be changed when the apparatus is defective.
U.S. Pat. No. 4,742,337, issued to Haag on May 3, 1988 discloses a LIGHT-CURTAIN AREA SECURITY SYSTEM. This specification teaches an area coverage security system that provides a xe2x80x9ccurtainxe2x80x9d for detecting a break in the light. The device further teaches the use of a series of transmitting and receiving strips wherein the transmitters send a signal that is reflected off of a reflection strip to be received by a receiver. The device provides a means for timing the signal (see col. 5, lines 32-48) to determine when a alarm should be sent, and thus providing sensitivity to keep the occurrence of false alarms small.
U.S. Pat. No. 5,583,334, issued to Baumann on Dec. 10, 1996, discloses a METHOD AND APPARATUS FOR THE DETECTION OF DEFECTIVE LIGHT TRANSMITTERS AND/OR RECEIVERS OF A LIGHT GRID FOR DETECTING OBJECTS IN A SURVEILLANCE AREA. This disclosure teaches a device having multiple light transmitters and the same number of light receivers that are positioned opposite of the transmitters. The device provides for the transmission of light by the transmitters and the reception of light by the receivers, with the beam of lights from the transmitter diverging to contact more than one receiver. The apparatus is then able to analyze the received signals to determine if an element (transmitter or receiver) is not operating properly.
U.S. Pat. No. 5,812,058, issued to Sugimoto et al., discloses a SECURITY SENSOR WITH BUILT-IN SIGHT. This invention teaches a security sensor having a receiver and a transmitter that are accommodated within a housing. See col. 3, lines 56-60. The security sensor is quipped with a sighting device in which the respective optical axes of the beam projector and receiver can easily and quickly be adjusted. The security device has an alarm whereby when the beam of light is broken, the receiver causes the alarm or warning display to so indicate.
In contrast to these patented systems, different manufacturing processes require different detection systems for varying product types. Some manufacturing production schemes require the product to be present during the operation and others may require the product to be absent. Thus, a sensor should also allow for detecting when a product is present and when a product is absent. The present invention provides a sensor mounting, reflecting, and protection device which satisfies the aforementioned needs.
A mounting plate for a light sensor with a reflective mirror, transmitting device and a receiving device. The reflective mirror, transmitting device, and receiving device are securably attached to the mounting plate of the invention so that aiming adjustments are not required. The permanent mounting of the transmitting device and the receiving device in alignment with the reflective mirror provide a stable environment that does not require realignment after the sensor has been moved. The mounting plate is designed with two mirrored panels that reflect the signal generated by the transmitting device and two filtering plates for limiting the divergence of the beam of light to provide greater secured coverage of the area with only one transmitter and receiver.
The present invention is particularly suited for mounting sensors that are used to monitor the absence of, or the presence of, product passing through the shaped sensing area. The present invention protects the sensors and reflectors from much of the manufacturing debris and thereby reducing the cleaning time normally associated with high production debris systems. The invention provides for fixed sensor and reflector alignments to eliminate user alignment of the system.
Accordingly, the present invention is directed to a sensor mounting device for the mounting of sensors, reflectors, debris guards, and beam masking to monitor product ejection with repeatability.
Yet another advantage of the present invention is directed towards a sensing device that can be mounted in any direction to accommodate many different types of machines and product detection.
A still further advantage of the present invention allows multiple devices to be mounted in a front to back configuration to obtain redundant sensing. The present invention may also be mounted in a side by side configuration to accommodate closely ejected multiple product systems where two or more parts ejected simultaneously.
One embodiment of the present invention includes a base that maintains alignment of the reflectors, sensors, and protective covers.
A further embodiment of the present invention adds debris guards to further protect the reflectors and sensors from debris.
Yet another embodiment of the present invention utilizes masks to block portions of the beam to de-sensitize standard sensor arrangements to eliminate small particle sensing.
Thus, the present invention utilizes reflected through-beam photoelectric sensing to detect product being ejected, poured, extruded, or otherwise expelled from equipment. The small particles, drops of oil or other debris that may be associated with the expelled product can be ignored by the sensor. The present invention accomplishes these advantages with a combination of mechanical and electrical connections mounted within a case that is not easily tampered with.